Duke Institute for Brain Sciences

Dr. Soo-Hong Chew

National University of Singapore

Imaging Genetics of Decision Making Under Uncertainty

Dr. Chew is an economist whose research lies at the intersection of decision science and the biological sciences (e.g., neuroscience, genetics). In this informal seminar, Dr. Chew will present results from two recent studies his group. Titles and abstracts of those studies are provided below.

A Neuroimaging Study of Preference for Strategic Uncertainty Robin CHARK and CHEW Soo Hong

We report the findings of an experimental study of preference for strategic uncertainty using neuroimaging. Participants decide whether to receive a specific amount for sure or enter either a matching pennies or a coordination game. We find that people have a general aversion to uncertainty arising in a competitive setting than in a cooperative setting and that this aversion is moderated by whether the uncertainty results from a randomized choice or a conscious choice of a strategic counterpart.

Specifically, participants choose to play the coordination game with a conscious player more often than they did against a randomized player and reverse this pattern when playing matching pennies. Consistent with our behavioral findings, increased amygdala and orbital prefrontal cortex activation are associated with participants valuing matching pennies less than coordination when played against a conscious opponent and valuing coordination less than matching pennies when played against a die.

Familiarity Breeds Risk Affinity: GABAergic Modulation of Neural Response to Familiarity Bias Robin Chark, Songfa Zhong, Shui Ying Tsang, Richard P Ebstein, Hong Xue, Soo Hong Chew

In making decisions under uncertainty, people have different propensity to take risk. They are said to display familiarity bias when their degrees of risk propensity increases with their familiarity with the underlying source of uncertainty. Building on evidence from past psychopharmacology studies showing that the administration of GABA agonists can enhance risk taking, we hypothesize that individual differences in familiarity bias may be explained by differences in anxiety regulation as modulated by the GABAergic system in the brain. We test this hypothesis across two studies. The first focuses on GABRB2, a gene for GABA_A receptors on which a class of diazepam anxiolytics acts). We find the homozygous major genotype (TT) of SNP rs1816072 in GABRB2 to be significantly associated in 325 Han Chinese with familiarity bias. In the second study, we recruit a subsample of 40 participants for a functional imaging study and investigate the neural substrate underlying how this SNP mediates familiarity bias. We replicate the dependence of familiarity bias on the homozygous major allele and further find that activation in the right amygdala correlates with individual levels of familiarity bias and, notably, is higher in participants with the TT genotype. This offers the first evidencethat GABAergic inhibitory circuits in the amygdala contribute to individual differences in familiarity bias.Taken together, we identify a biological mechanism linking a GABA gene and the amygdala towards a deeper understanding of a classical behavioral economic paradox - familiarity bias.

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